Conventionally, a method of joining two components airtightly is disclosed in, for example, Japanese Patent Application Laid-Open Publication No. 2006-151362.
The joining method disclosed in the Publication is to join a valve seat to a housing by inserting the valve seat in a hole of the housing and crimping a part of the housing.
Thereby, airtightness between the housing and the valve seat is secured by using a contacting part of an inner wall surface of the housing and a perimeter surface of the valve seat as a sealing part.
Moreover, press-fitting one component into another component is known as another method of joining two components airtightly.
However, when two components are joined by press-fitting and a first component has a thin cylindrical shape, the first component receives a load from a second component inwardly in a radial direction by the press-fitting, and since a tip side in a press-fitting direction of the first component deforms inwardly in the radial direction and may escape from the second component, a problem arises that a surface pressure for securing the airtightness of the sealing part cannot be fully obtained.